Urethane elastomers are produced in large quantities from various isocyanate terminated prepolymers by reaction with a hindered diamine. Historically, 4,4'-methylene bis (o-chloroaniline) (hereinafter "MOCA") has probably been the most widely used hindered amine. However, MOCA is a carcinogen suspect agent, and, as a consequence, taking the necessary safety precautions to safeguard the health of workers substantially increases the cost involved in producing elastomers using MOCA as the hindered amine. Another hindered amine that has also seen considerable use is 4,4'-methylene bis (methyl-anthranilate) (hereinafter "MBMA").
So far as is known, unhindered diamines have not heretofore been used for reaction with an isocyanate terminated prepolymer to produce an elastomer. Pot life is short, only a few minutes, even when MOCA and MBMA are used as the diamines. In a recent experiment wherein an attempt was made to produce a urethane elastomer from an isocyanate terminated prepolymer and an unhindered diamine the pot life was estimated to be five seconds; the specific unhindered diamine used was 4,4'-methylene dianiline (hereinafter "MDA").